settings to customize docker runtime/environment

we use minikube to start docker containers locally. It takes the setting of 4 environment variables, for the docker daemon to be connected. However, even though AWS toolkit relies on docker to run local invocation, it does not provide any settings in the plugin to customize docker daemon detection.

Even after I include the env section in my launch.json for run config, with those 4 environment variables defined as they should be, AWS toolkit keeps asking for docker :(

## Steps to reproduce the issue

## Expected behavior

## System details (run the `AWS: About Toolkit` command)

- OS: MacOS 10.15.7
- Visual Studio Code version: 1.67.2
- AWS Toolkit version: 1.38.0

Start by tracing how the AWS Toolkit detects Docker for local invocation and how launch.json environment variables are handled. Done means users can configure Docker daemon detection for a minikube-backed environment and local invocation no longer incorrectly asks for Docker.

Written by the indexing model from the issue text.